Our approach is not simply to look for life or extraterrestrials. It is a more global process with many different angles of attack. We can work on the ingredients and mechanics to try to replicate life as we know it, under realistic scenarios with the conditions that may have been available on Earth at that moment. There may have been mega impacts, specific geophysical conditions, volcanic activity, river flow and so on. All these elements must be considered in a consistent logical order to work. And while I’m not personally doing research on that specifically, it is essential to fully understand life as we know it on Earth. Is it the perfect starting point to understand other systems of planets or Solar System objects? Then, for example, a simple question such as ‘is there water on other planets’ is crucial. Venus has no water, but is it because there never was or has it gone? Maybe we will find that having water delivered and remaining on a planet is rare. Or maybe other solvents can be used as well for a chemistry of life.
Practically we are steadily building a reliable framework to understand all aspects of life as we know it. From this solid baseline we can try to extrapolate that framework to another planet, which might be more massive, or have a higher pressure, or have bigger oceans or different planetary chemistry. We can also imagine an experimental setup for trying to replicate some of the chemistry that is happening on another body. Think about Enceladus. We know there is water there. We know there is a rich chemistry going on but it will be different from that expected on early Earth, because you don’t have similar UV radiation for example. The same for Titan and Europa. For each case, it’s always the same; for example, what is the solvent? Start from what we know, change it little by little and develop a more comprehensive picture.
Ultimately, we would like to know, if you look at a star, what do the planets on that star look like? Right now, 6,000 confirmed exoplanets is a large number but ridiculously low given the number of stars in the Galaxy. Further we’re completely biased regarding the kind of planet that can be detected by the transit method (in most cases) or their velocity (in some cases) with a decade-old technology. I would really like to find more planets like the Earth because they’re missing in our catalogue. It’s a bit frustrating, looking back over the past 30 years, to realize that we still know so little about how common planet configurations like our Solar System are.
Another key point is timescale. On Earth, we needed time for complex life to evolve. The Cambrian explosion was only half a billion years ago, but life first appeared 4 billion years ago. So maybe evolved life with a high consciousness capability is extremely rare in our Galaxy.